1. FIELD OF THE INVENTION
This invention relates to water filters, particularly tap water filters which are constructed to removably mount onto a drinking water faucet.
2. DESCRIPTION OF THE PRIOR ART
Increasingly, the quality of drinking water has become a vital concern for a growing segment of the population. Today, with reports of environmentally unsafe material contaminating ground water, there is every reason for persons to suspect the water that they consume. This concern extends beyond well water systems to include many municipal water systems which were built at a time when bituminous pitch was used to line water pipes as a corrosion preventative measure. Consequently, it is possible that water received at a tap water faucet may contain any number of undesirable contaminants, including solid debris, chemical contamination, and biological contamination.
There are several ways to ensure that drinking water is potable. One way is to purchase distilled water or water which is guaranteed pure from an uncontaminated spring. This proves to be too expensive and generally impractical for most people. A second way is to purchase a personal water distillation unit. While it is the case that these units are becoming increasingly more common, their extreme inconvenience and expensiveness point out the pervasiveness of the water quality problem which is growing more alarming each day. A third, and most reasonable, way is to purchase a filter which is relatively inexpensive to filter water at the tap. This would be particularly useful if it is in the form of a portable filter so that it may be mountable to any tap water faucet as the need may arise.
The concept of filtering drinking water at the tap was proposed by Johnston, U.S. Pat. No. 727,374, issued May 5, 1903. Johnston's device is of generally cylindrical shape including a faucet attachment portion having internal threads for threading onto external threads of a faucet. A filtering portion is disposed downstream from the faucet attachment location. The filtering portion contained, in sequential order from the faucet attachment location, a perforated metal sheet, a filtering media and, finally, a hemispherically-shaped filter-plate or wire-gauze. While the device taught by Johnston is practical for a permanent installation, it is not practical for a portable, disposable water filter which can allow anyone to carry it with them and be very easily installed and removed whenever the need is presented, such as when the user is out of town in a hotel room, or when the user is at work.
Other tap water filter systems which have been proposed, but are impractical as a portable, disposable tap water filter because of the size and complexity of their structure, are: U.S. Pat. No. 1,287,755 to Rorer which utilizes dual shaped pipes; U.S. Pat. No. 1,774,004 to Haslett which discloses a multi-segmented filter; U.S. Pat. No. 2,314,357 to Lehman which discloses a filter selective between a spray and a stream setting; U.S. Pat. No. 3,204,770 to Brink which discloses a clampable faucet fitting and a channel filter to ensure complete water flow therethrough; U.S. Pat. No. 3,760,951 to Mansfield which discloses a threaded cone which must be screwed into a particular faucet in order for the filter to be attachable to the faucet; U.S. Pat. No. 4,001,120 to Gelman et al which discloses a structure that screws into the aerator threads or a faucet and has a valve to selectively bypass filtering in order to extend the filter life; and finally, U.S. Pat. No. 4,288,325 to Lieberman which discloses a threadable faucet attachment structure and a filter having selectable water stream or spray output.
Tap water filter systems which are less structurally complicated, but yet are still impractical as a portable, disposable tap water filter either because the connection structure to the faucet requires too much effort to force a resilient member onto the faucet or because of potential damage to the faucet as mounting set screws are tightened, are: U.S. Pat. No. 2,328,381 to Jaffe which discloses a tap water filter having a faucet connection structure utilizing set screws for fastening thereto; U.S. Pat. No. 2,368,035 to Moore which discloses a faucet connection structure utilizing an annular lip which is retained by a cap unit; U.S. Pat. No. 3,255,691 to Schwartz et al which discloses a beverage flavoring device having a resilient member which is mountable on a nozzle; and, finally, U.S. Pat. No. 3,707,236 to Takebayasi which discloses a resilient cap having an inner resilient cylinder structured to mount onto a faucet.
What is needed in the art is a practical, portable, disposable tap water filter for personal use which is easily and readily mountable to and removable from any tap water faucet as the need may arise. Accordingly, such a tap water filter must be small, uncomplicated, inexpensive, not damaging to the faucet, and very easy to mount on and to remove from the faucet.